This invention lies in the field of liquid hydromatic brake systems. More particularly, it is concerned with a hydromatic brake assembly that is made out of a single pair or a plurality of pairs of unitary rotor and stator elements which can be housed inside a pair of end walls to provide brakes of different braking capacity by the addition or subtraction of pairs of rotor-stator pairs.
Hydromatic brakes have been known and used heretofore in automotive and truck equipments and for dynamometer purposes. They have also been used in oil well drilling operations as a control over the hoist mechanism when large and heavy strings of drill pipe are being lowered into the bore hole into the earth. The continued use of conventional friction brakes has provided to be unsatisfactory so that the use of hydromatic brakes has increased in recent years.
The design of hydromatic brakes and power absorbers is well known and these have been widely used in several of the dynamic vehicle arts.
In general they comprise a pair of relatively rotating members. One of them is fastened to a rotating shaft, the other is held stationary with respect to a housing which supports the shaft rotatably in appropriate bearings. Each of the rotor and stator elements includes an annular cavity, the cross section being in the shape of approximately a half circle. There are a plurality of vanes inserted across the cavity. These are generally inclined at an angle of approximately 45.degree.. In the rotor cavity they are directed in the direction of rotation of the rotor. In the stator cavity the vanes are directed against the direction of rotation. The cavities of the rotor and stator are substantially mirror images of each other, and the two elements are face to face with a relatively narrow selected spacing between the two elements.
There are a plurality of holes that are drilled through the stator vanes and through the back portion of the stator elements. The housing is designed to provide a space behind the stator for inlet liquid, which flows from the inlet liquid space through these holes in the vanes into the center formed by the two cavities in the stator and rotor elements. The vanes tend to cause a very high degree of turbulence in the brake liquid, which turbulence generates energy loss and heat which tends to raise the temperature of the liquid. In the prior art the liquid flows out of the cavities through the space between the two elements and into an exit pipe or conduit. It then goes to a heat transfer device where the liquid is cooled and returned back into the inlet liquid space to be passed again through the cavity.
In the prior art the designs have been based on controlling the flow of liquid through the apparatus by means of adjustment (by shims or otherwise) of the spacing between the rotor and the stator. In this device the controlling gap through which the liquid flows, is in the annular space between the outer circumference of the rotor and the inner face of the overhanging lip. Since these can be machined precisely before assembly, there is no need for any means to adjust this gap spacing and therefore the apparatus is much more simple to assemble. Also, in this improved apparatus the system of multiple rotors and stators is made up of a desired plurality of identical single rotor and stator elements and stacking them up axially with proper spacing, etc. to assemble a unit of as large a capacity as may be desired.
In this design the stator has a planar annular flange on the outside of the lip which is clamped between a pair of end walls to provide a closed housing around the stator and a rotor, which can be assembled on a shaft inside of the housing. Where more than a single pair of rotors and stator is required additional space is provided by means of short cylindrical flanged tubes of appropriate length, which are placed between the separate stator flanges to complete the housing. All parts are bolted longitudinally to provide a closed container.
Heretofore hydrodynamic brakes were usually designed at fairly fixed and few load ratings. The intricacy of the castings for the stator and rotor required that a user adopt a brake which may be substantially more than the actual design load requirements. In this invention the entire assembly is simplified and there is considerably greater ease of assembling, without entire redesign of units of various numbers of stators and rotors to provide increased or reduced capacity.
It is a primary object of this invention to provide a design of hydromatic brake which utilizes one or more pairs of identical unitary single rotor elements corresponding single stator elements, assembled in selected numbers of pairs and spaced axially of each other to provide brake systems of different braking capacity.
It is a further object of this invention to provide a design of rotor and stator in which the resistance to flow of liquid through the hydromatic brake is controlled by the original machining of the rotor and stator instead of having to be adjusted individually during the assembly operation.
It is a still further object to provide a design of hydromatic brake having two rotors and two stators, and which can be generated in the reverse direction of shaft rotation simply by interchanging the positions of stators and rotors.
These and other objects are realized and the limitations of the prior art are overcome in this invention.